1. Technical Field
This disclosure relates to electric machines, and more specifically to synchronous systems that generate reluctance and magnet torques.
2. Related Art
Permanent magnet machines may supply small or large amounts of power. These rotating machines convert mechanical energy into electrical energy through a rotation. Some rotating machines may convert electrical energy into mechanical energy. A rotor, which carries fixed permanent magnets, rotates in a magnetic field that induces an electromotive force in the windings of the stator core.
In vehicles, interior permanent magnets may be mounted near the outer circumference of the rotor that produces a rotating field. The rotor punching bridges that extend between the cavities that house the permanent magnets may counter the centrifugal force that may be directed away from a center or axis. As the revolution about the axis increase, centrifugal force increases and the need for stronger bridges increase. With stronger bridges, leakages flux passing though these bridges increase, which decreases motor performance.
In some applications, permanent magnet machines may not provide a good power factor at slow speeds. In other applications, the operating temperature of a permanent magnet machine may be limited. At some temperatures, permanent magnets may be become demagnetized.
In other applications the back electromotive force in the stator winding induced by the permanent magnets may limit motor speed. Performance limitations may come at a high cost, as the cost of the rare-earth permanent magnets can be substantially higher than those of iron and copper.